Mitsubishi Electric M800VW Series Programming Manual page 140

M800V/M80V Series PLC Programming Manual (1/2)
6 Explanation of Instructions and Functions
6.9 PLS/PLF Instruction Behavior in the State from PLC STOP to RUN
Behaviors while "#6456/bit2" (PLS/PLF instruction holding PLC in STOP state valid) is set to "1"
This behaves in the same manner as the M7 Series.
Hold "previous scan state of PLS/PLF instruction" at PLC STOP.
When RUN is executed from PLC STOP again, PLS/PLF instruction is executed with "previous scan state of PLS/PLF
instruction" at PLC STOP. Therefore, even if the contact point of PLS instruction is ON at PLC STOP, the device of one scan
PLS instruction argument stays OFF when RUN is executed from PLC STOP.
[Ladder]
X0
PLS M0
Note
(1) When setting "#6456/bit2 (PLS/PLF instruction Holding PLC in STOP state valid)" to "1" and creating a sequence pro-
gram which execute PLS/PLF instruction of the same device several times for one scan, this holds the PLS/PLF instruc-
tion near the end of sequence program at PLC STOP. (Not the last executed PLS/PLF instruction state.) Then, when
performing PLC RUN again, the held PLS/PLF instruction state is used as the previous scan state.
Because of this, when creating a sequence program which execute PLS/PLF instruction of the same device several times
for one scan, be aware that the PLS/PLF instruction may not behave in a way as intended.
In the multi-project environment, it will be in the same manner as when creating a sequence program to execute PLS/PLF
instruction in the each project with the same device of common devices for projects (X, Y, R, ZR, etc.).
In this case, PLS/PLF instruction state which the number of projects is greater is held, and it is used as "previous scan
state of the PLS/PLF instruction" of each project.
[Ladder]
SM400(always ON)
CALL P0
X1
PLF M0
FEND
X0
PLS M0
RET
END
[Timing chart]
X0
END
ON
X0
ON
M0'
M0 OFF
(Saves PLS
instruction status)
M0 remains OFF because
M0' = OFF -> X0 = OFF.
M0' saves X0 = OFF at the
same time.
[Timing chart]
X0
PLS M0
X1
END
OFF
X0
OFF
X1
ON
M0' OFF
OFF
M0"
ON
OFF
M0
(Saves PLS
M0 turns OFF because
instruction status)
M0'' = OFF -> X1 = OFF.
M0'' saves X1= OFF.
(Saves PLF
instruction status) M0 turns ON because
M0' = OFF -> X0 = ON.
M0' saves X0 = ON.
119
X0
PLS M0
PLC
PLC
RUN
STOP
END
Holding M0'
M0 remains OFF because
M0' = ON -> X0 = ON.
M0' saves X0 = OFF at the
same time.
PLC
PLC
RUN
STOP
PLF M0
END
State of M0' is
applied
M0 remains OFF because
M0' = ON -> X0 = ON.
M0' saves X0 = ON.
PLS M0
END
X0
PLS M0
X1
PLF M0
END
OFF
ON
M0 turns ON because
M0'' = ON -> X1 = OFF.
M0'' saves X1= OFF.
IB-1501667-B